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 Home > JCEDLib > QBank > Collection > CQs and ChPs > CQs > CQ Library >
Library of Conceptual Questions (CQs): Stoichiometry
In lab, we often titrate a colorless solution of H2SO4 and H2O2 with a purple solution of KMnO4. The first permanent trace of purple color indicates the end point. The reaction is

5H2O2 + 2KMnO4 + 3H2SO4 -> K2SO4 + 2MnSO4 + 5O2 + 8H2O

Which is the limiting reactant in this experiment?

(a) H2SO4
(b) H2O2
(c) KMnO4
(d) O2
(e)K2SO4

Which of the following samples could be methane, CH4?  A sample that contains

 (a) 0.40 mole of H2  molecules and 0.10 moles of C atoms.
 (b) 0.40 mole of H atoms and 1.0 x 1023 C atoms.
 (c) 4.0 g of H atoms and 1.0 g of C atoms.
 (d) 25% hydrogen, by weight, and 75% carbon, by weight.
 (e) All of these samples could be methane.


Which is the limiting reagent when 9 Ca atoms and 8 H3PO4 molecules react and produce 3 molecules of Ca3(PO4)2 and 9 molecules of H2?

 (a) Ca
 (b) H3PO4
 (c) H2
 (d) Ca3(PO4)2
 (e) None of these.


Which statement correctly describes 1.0 L of a colorless solution that contains phenolphthalein if the addition of one drop (0.05 mL) of 1.0 M NaOH causes the solution to turn pink?

 (a) The colorless solution is almost neutral.
 (b) The colorless solution contains a base with a concentration of at least 0.1 M.
 (c) The colorless solution contains a weak acid with a concentration of at least 0.1 M.
 (d) The pH of the colorless solution is at least as high as 10.
 (e) The pH of the colorless solution is at least as low as 2.

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